A foreign originating mailpiece, which bears invalid postage and is accompanied by a letter of explanation from the origin postal administration, is to be rated as an unpaid postal item. Under those circumstances, the addressee should be asked to (1) pay the requisite postage due; (2) disclose the sender’s name and address; and (3) surrender the envelope. After the mailpiece has been tendered to the addressee, the delivery Post Office facility should send the envelope (or the entire article, if refused by the addressee) with the letter of explanation and the sender’s name and address (if disclosed by the addressee) to: